One of the problems with building transmitters and receivers is the accuracy of calibration. This circuit provides calibration points at 1Mhz, 100kHz, 10kHz & 1kHz intervals. There is nothing original about the circuit, it uses standard cmos chips, one as the oscillator at 1MHz and three decade dividers to give the other points. For ease of construction I have used Veroboard^TM.

It is important to select the B version of the cmos chips. All components are readily available from a whole range of suppliers.